Cleaning sheet



April 1961 R. E. MILLER 2,980,941

CLEANINGSHEET Filed Dec. 8, 1958 CAPSULES CONTAINING LIQUID CLEANER FIG.2 CAPSULES CONTAINING LIQUID CLEANER Qi/FuLLERs EARTH PARTICLES 3CAPSULES CONTAINING LIQUID CLEANER INVENTOR ROBERT E. MILLER HISATTORNEYS .CLEANING SHEET Robert E. Miller, Dayton, Ohio, assignor toThe National Cash Register Company, Dayton, Ohio, a corporation ofMaryland I Filed Dec. s, 1958, Ser. No. 778,643 8 Claims. c1. 15506)This invention relates to a cleaning sheet including a base web ofabsorbent fabric, and the base web fabric in cluding, in or on it, solidparticles of an adsorbent material such as fullers earths, interspersedwith or in juxtaposition to minute pressure-rupturable capsules eachcontaining a liquid soil remover, said liquid preferably being of anevaporable nature, but not necessarily so. The capsules are rupturedwhen the cleaning sheet is rubbed against an article to be cleaned,freeing the liquid soil remover, which, together with the adsorbentnature of the particles of solid material and the absorbent nature ofthe fabric base web renders the cleaning sheet exceptionally efiicientfor its purpose, as the removed soil is thereby retained on or in thesheet either by the base web fabric or the adsorbent particles.

The fact that the liquid soil remover is contained in capsules keeps thepaper in a dry state, as far as superficial contact is concerned, untilused, and such containment prevents the evaporation of the liquid soilremover if such is of a volatile nature. The liquid soil remover used inthe capsules is such as to enable it to remove oily marks of a surfaceof a material to be cleaned. The com-' bination of an absorbent base webfabric, adsorbent particulate material, and a liquid soil remover, isknown and is disclosed in United States Letters Patent 995,904, whichissued on the application of John R. Rentz, June 20, 1911, but in thatdisclosure the soil removing liquid was not encapsulated and,consequently, was free to evaporate and rendered the sheet damp to thetouch. In the present invention, the cleaning sheet feels dry and can bestored indefinitely without deterioration, by evaporation, of the liquidmaterial.

It is within the scope of the invention to have particulate adsorbentsolids of different kinds mixed together in the paper, and, likewise, itis within the scope of the invention to have a mixture of capsulescontaining different soil-removing liquids, or to have a mixture ofsoil-removing liquids in the same capsules.

The invention will be described with reference to the drawing, of which:

Fig. 1 is a diagrammatic cross-sectional view of the form of theinvention in which the adsorbent material is in a coating next to theweb (of paper) which is overlaid with a coating of the liquid-containingcapsules;

Fig. 2 is a diagrammatic cross-sectional view of the for-tn of theinvention in which the adsorbent material and the capsules areintermixed and applied as a coating to the web (of paper);

Fig. 3 shows the fibrous web (of paper) impregnated with' the adsorbentmaterial, the web being overlaid with a coating of the capsules.

The absorbent base web preferably is made of untreated paper fibers, asshown in Figs. 1 and 2, although the solid adsorbent particulatematerials may be mixed With the pulp before the paper sheet is formed,and thus become entangled in the paper fibers of the sheet, as shown'inFig. 3. An incorporation of adsorbent material in the pulp fibersthemselves before they are made into a paper sheet, is the subjectmatter of an application for I United States Letters Patent, Serial No.552,237, filed by Leon Paquin, on November 29, 1955, which issued intoUnited States Patent No. 2,902,399 on September 1, 1959, wherein analumina-silicate material, of an adsorbent nature, is formed in the pulpsuspension before the paper is made from the pulp fibers. Another way ofincorporating the particulate adsorbent material in paper is simply tostir it in the pulp fiber suspension before it is made into a papersheet. The preferred method, however, is to coat the solid adsorbentparticles on a sheet of paper,

' either with the liquid-containing capsules interspersed therein, asshown in Fig. 2, or coated over such particu-- late absorbent coatingafter it is applied to the sheet and dried, as shown in Fig. 1.

Among the solid particulate materials which may be used are thewell-known fullers earths, such as montmorillonite, kaolin, bentonite,natural or artificial sodium aluminum silicate zeolite materials, andartificially activated forms of the aforementioned materials. There area large number of such adsorbent materials which may be used, but, forthe purposes of the preferred embodiment of this invention, attapulgiteis chosen as being very suitable for such purposes as it is veryefiicient and is readily obtained from natural deposits.

In the United States Patents 2,581,186, which issued on the applicationof Barrett K. Green, on January 1, 1952, and 2,641,557, which alsoissued on the application of Barrett K. Green on January 9, 1953, thereare disclosed papers which are coated with zeolite material and withattapulgite material, respectively, and which, if they had appliedthereto a coating of pressure-rupturable capsules containing asoil-removing liquid, would serve the purposes of this invention.

, The principal object of this invention is to provide a cleaning sheetof an absorbent base web fabric, so coated with adsorbent particulatematerial and with capsules containing soil-removing liquid, that, byrubbing it on the surface of an object to be cleaned, it is activated byrupture of the capsules and release of the liquid soil remover, toloosen and remove soil, particularly of an oily nature,

which removed soil is adsorbed and absorbed by the cleaning sheet. Itwill be understood, therefore, that the cleaning sheet has the threecharacteristics of solvent action, adsorbent characteristics, andabsorbent characteristics, which operating in a concerted relation provemost effective for the purposes stated.

There are several methods known for incorporating the soil-removingliquid within the pressure-rupturable capsules, one of them beingdisclosed in United States Letters Patent 2,800,457, which issued on theapplication of Barrett K. Green and Lowell Schleicher on July 23, 1957,and another being disclosed in United States Letters Patent 2,800,458,which issued on the application of Barrett K. Green on July 23, 1957.

In the preferred embodiment of the invention, it is proposed to make theliquid-containing pressure-rupturable capsules of a diameter of under 10microns, by .a process similar to that disclosed in the Green andSchleicher United States Patent No. 2,800,457, wherein a large amount ofliquid is contained in only the least necessary encapsulating wallmaterial that will keep the liquid from being dissipated during ordinaryhandling and storage conditions, before being required for use.

In the preferred embodiment, grams of diethyl-,

7, and the temperature being kept at about 55 degrees centigrade,throughout the process, until the capsules are finally formed. To"thissolution-minture is added 60 milliliters" of a 1%, by weight,aqueous solution of polyvinylrnethylethermaleic anhydride copolymer,havingj'a pH of 9, andthe'n' adjusting the whole of theflinixturesolutionto pH 9. Finally, thereis' added850 grams of water and, afterthorough incorporation of theing're'die'nts, the pH is lowered to 416,by the addition" of a 10%", by weight, aqueous solntion'of acetic acid,drop by drop, with continuous stirring, which stirring is continued asthe temperature then is dropped to ,14 degrees centigrade, whichsolidifies the walls on the formed capsules, after which there isstirred in 10 milliliters of a 25% by weight, aqueoussolution ofglutaraldehyde. The capsules which now contain the liquid soil removerare now corn plete, and the water content in which they are suspendedmay be adjusted to provide a coating slurry of the proper viscosity, andthey maybe applied to paper which has in or on it the absorbentparticulate material.

A second method of making the capsules involves the use. of carbontetrachloride, which is added, drop by drop, in the amount of 150milliliters into a mixture consisting of 180 grams of a 11%, by weight,aqueous gum -arabie solution, 180 grams of a 11%, by weight, aqueousgelatin solution, 40 milliliters of a 2%, by weight, aqueous solution ofpolyethylenemaleic anhydride copolymer at pH 9, and 1200 milliliters ofwater, the whole thereafter being adjusted to pH 7, the temperaturebeing 7 maintained at '35 degrees centigrade. The materials arecontinuously stirred in a manner to reduce thedrop size of the carbontetrachloride to between 50 and 400 microns, after which the pH islowered to 5 to form an;initial capsular wall around each droplet. ThepH then is raised to 5.5, using a 20%, by weight, aqueous solution ofsodium hydroxide, and thereafter 40 milliliters of a 2%, by weight,aqueous solution of polyethylenemaleic anhydride copolymer is added witha slight rise to pH 6 noted. Immediately thereafter, the pH is adjustedto 5.3 and, with continued stirring, the temperature is allowed to fallto degrees centigrade. By this time, a second and thicker wall of thecapsular material has formed around the initial wall of each partiallyformed capsule. Thereafter, l5 ccs. of 25%, by weight, aqueous solutionof glutaraldehyde is added, and the stirring is continued for severalhours to harden the then-finished capsules. The suspension of theso-rormed capsules may have the water adjusted to give the propercoating conditions desired to give the necessary thickness of thecoating on the base web fabric, which coating should be a fewthousandths of an inch in thickness.

The above two encapsulating techniques may be used to encapsulate othersoil-removing liquids such as petroleum distillate (including fractionssuch as gasoline, kerosene, and light lubricating oil), toluene, xyleneand other liinown water-soluble preferably volatile soil-removing uids.

A paper coating composition, including as the adsorbent particulatematerial, attapulgite, is set forth in the above-mentioned United StatesLetters Patent 2,641,557, of Barrett K. Green, in which 20%, by weight,of paper coating starch is cooked in water at 200 degrees Fahrenheit forfifteen minutes and allowed to cool to room temperature, followed by thedispersion therein of four parts, by weight, of a dispersion of 1 part,by weight, finely divided attapulgite, in three parts, by weight, of

water, to one part, by weight, of the starch solution.

The resultant mixture is applied to the selected paper at roomtemperature and dried, the coating preferably being of a thickness, moreor less, of .001 to .005 of an inch. Other binders than the starch maybe used, such being well known in theclarcuating-of-paper art, ex amplesbeing casein, polyvinyl alcohol, animal glue, and obvious equivalents.The making of paper, including as the'adsorbent particulate material,zeolite, is described in the-beforementioned patent relating tozeolite-coated paper. The invention is not to be deemed limited in scopeby the. particular soil-removing materials and coating compositionsdescribed, as the invention resides in the combination of the absorbent"base web fabric, the adsorbent-solid particulate matter, thereon ortherein, and pressure-rupturable minute capsules containingsoil-removing liquid positioned thereon or therein in juxtaposition. I

It will' be understood from the foregoing that the cleaning sheet, whilecontaining'a considerable amount of available liquid soil-removingmaterial, feels dry to the touch, and will remain in that conditionuntil activated by being rubbed on a surface of material to be cleaned.

What is claimed is: y i

1. As an article of manufacture, a'cleaning sheet, in cluding anabsorbent fabric web provided with a profusion of minutepressure-rupturable capsules, each cap- 'sule containing aliquid soilremover, and further provided with particles of adsorbent material foradsorbing the liquid and soil removed thereby, the cleaning sheet bybeing rubbed against the surface of an article to be cleaned, resultingin the rupture of the capsules, thus releasing the liquid to remove thesoil'from the object to be cleaned, the liquid and included soil beingadsorbed on the adsorbent particles and absorbed by the fabric web. 1

2. The cleaning sheet of claim'l in which theparticulate material andcapsules are applied to the web as separate coatings in contact. I

- 3. The cleaning sheet of claim 1 in which the particulate material andcapsules are interspersed and applied to the web as a coating.

4. The cleaning sheet of claim 1 in which the web is paper.

5. The cleaning sheet of claim 1 in which the particulate material is anadsorbent of water-insoluble liquids, and in which the liquid is waterinsoluble.

6. The cleaning sheet of claim 1 in which the web is paper and theparticulate material and capsules are applied thereto as separatecoatings in contact.

7. The cleaning sheet of claim 1 in which the web is paper and theparticulate material and capsules are in' terspersed and applied to thesheet as a coating.

8. The cleaning sheet of claim 1 in which the web is paper, in which theparticulate material is interspersed in the fabric thereof, and in whichthe capsules are applied to the paper as a coating.

References Cited in the file of this patent UNITED STATES PATENTS995,904 Rentz June 20, 1911 1,056,067 Sporer Mar. 18, 1913 1,143,614Criswell June 22, 1915 2,641,557 Green June 9, 1953 2,730,457 Green etal. June 30, 1953

1. AS AN ARTICLE OF MANUFACTURE, A CLEANING SHEET, INCLUDING ANABSORBENT FABRIC WEB PROVIDED WITH A PROFUSION OF MINUTEPRESSURE-RUPTURABLE CAPSULES, EACH CAPSULE CONTAINING A LIQUID SOILREMOVER, AND FURTHER PROVIDED WITH PARTICLES OF ADSORBENT MATERIAL FORADSORBING THE LIQUID AND SOIL REMOVED THEREBY, THE CLEANING SHEET BYBEING RUBBED AGAINST THE SURFACE OF AN ARTICLE TO BE